Super resolution playback involves displaying images at higher resolution than what is transmitted. Super resolution allows the display of a higher quality image in the same amount of bandwidth by using information on how the lower resolution (broadcast) image was created. However, practical use of super resolution with current broadcast encoding is limited.
A major issue arises in the transmission of images. Many techniques reduce the bandwidth on transmission, often resulting in loss of the high frequency content. Without any high frequency content, the super resolution processes cannot easily recover any further details. This defeats the purpose of super resolution that aims to increase the detail.
A common broadcast technique to reduce bandwidth is generating an interlaced picture. This can reduce the bandwidth by one half. For example, 1280×720 progressive images take as much bandwidth as a 1920×1080 interlaced picture. At the time it was developed, interlacing solved the issue of flicker caused by large bright areas on the display by allowing a higher frame rate for a given amount of resolution. Interlacing refreshed these areas more frequently, which reduced flicker. When the primary display device was a CRT, no special processing was required to handle the interlaced format. The raster scan was simply shifted by ½ line between fields to maintain the correct vertical alignment. However, fixed pixel devices, unlike cathode ray tube devices, have to de-interlace the fields prior to display. This has led the move to progressive image formats for transmissions. In addition, images transmitted across the Internet for display on computing devices, generally transmit as progressive images.
Interlace transmission can be thought of as an extreme example of how to encode an image for super resolution playback. Each field is a lower resolution version of the original and contains alias components that change from field to field. The deinterlacer needs to know how it was encoded or which field contains even or odd lines and whether there is motion. Unfortunately, interlaced transmission is difficult for typical computer devices to display without sophisticated per pixel processing.
What is needed is a method to reduce high resolution images to a lower resolution image in a way that is compatible with existing progressive video playback while allowing for the higher resolution images that are possible using interlaced transmission.